We propose to develop an effective ultrasound-based real-time brachytherapry treatment planning system that improves brachytherapy outcomes through better dose coverage, reduction in manual workload, and shorter treatment planning process and overall procedure duration. Our system concept incorporates innovations for: (1) dynamically refining the seed placement plan during brachytherapy based on ongoing cumulative seed placement deviations, (2) generating optimized dose plans, automatically localizing actual needle placements, and (3) improving prostate segmentation. The proposed ultrasound system transitions research results from an MRI-based brachytherapy treatment planning system being developed in a companion effort at Brigham & Women's Hospital (BWH). This phase I SBIR program focuses on the treatment planning aspects of our solution-demonstrating the feasibility of dynamically refining seed placement plans in a practical transrectal ultrasound video processing system. This effort will develop the processing software and interface for such a prototype system and will conduct lab experiments on ultrasound data collected from actual procedures. A proposed phase II effort will incorporate the additional improvements of MRI/ultrasound registration and automated ultrasound image processing and will conduct surgical experimentation in parallel with conventional ultrasound-guided brachytherapy systems. The proposed commercialization path consists of licensing technology to image-guided therapy system vendors. PROPOSED COMMERCIAL APPLICATION: We propose to develop an ultrasound-based real-time brachytherapy treatment planning system for improving brachytherapy outcomes for the patient and simplifying the workload for the surgeon. Ultrasound-guided brachytherapy is the most common form of guidance for such prostate treatments due to ultrasound's low cost and high availability. Our proposed developments are aimed at improving such procedures by providing dynamic treatment plan refinements and reducing manual planning workload in the image-guided feedback loop. As a low-cost workstation that directly processes ultrasound video data our proposed system is expected to exhibit favorable cost-benefit advantages for brachytherapy procedures.